The Earth's magnetic field (magnetosphere) is a gigantic invisible shield surrounding the Earth, which protects the planet from solar radiation. The invisible forces extend from the Earth;s poles for thousands of kilometers into space (magnetosphere). The Earth's magnetic field is generated in the interior of the Earth by electrical currents flowing in the liquid iron and nickel core of the Earth's interior. The following explains how the Earth's magnetic field protects against solar radiation
The earth's magnetic field deflects the flow of plasma ejected by the Sun. There are two regions in the magnetic poles known as the polar cusps, where energetic particles precipitate along magnetic field lines into the Earth's magnetic poles. The solar wind carries a stream of highly energetic particles, which interact with the Earth's magnetic field. These particles create luminous light displays (Auroras) at the Poles; however, these particles can be highly dangerous for unprotected astronauts, and damaging for orbiting satellites. The solar wind can potentially damage airplane flights, GPS systems and electric power grids.
Earth´s magnetosphere interacts with particles from the Sun that arrive via the solar wind. Most of these particles enter the Earth following field lines which open and join to those of the Sun, allowing the solar wind into the Earth´s magnetosphere. The Sun also releases enormous amounts of energy and material in coronal mass ejections (CMEs). These CMEs send a hail of radioactive particles into space. Once again, the Earth’s magnetic field protects us, sending the particles away from the planet, and protecting us from being irradiated.
An alignment of planets which took place on January 2008 allowed scientists to compare the shielding protective effects of the Earth's magnetic field with that of the naked atmosphere in Mars. Using ESA's cluster and Mars Express missions, scientists compared the loss of oxygen in both Mars' and Earth's atmospheres, while they were being hit by a stream of solar wind. They noticed that the rate loss of oxygen on Mars was 10 times that of Earth´s increase. This explains the present state of the Martian atmosphere, and proves the effectiveness of the Earth´s magnetic field at deflecting the solar wind and protecting the atmosphere.
Scientists believe that the Earth's magnetic field is generated inside the Earth by a liquid outer core composed or iron and nickel, surrounding the solid inner core. There, convection currents generate electric currents, creating a magnetic field. The magnetic field protects the planet from charged particles coming from outer space, deflecting these particles through field lines, surrounding the planet, and into the Earth's Poles.
According to science.nasa.gov, the Earth's magnetic field is changing, and has weakened by 10% since the 19th century. Sometimes, the fields completely change places; the North Pole becomes the South Pole and vice versa. This occurs, on average, every 3000,000 years; the last occurred 780,000 years ago. During this event, the field lines become twisted and tangled, and the Poles might appear in different places of the world; however, experts believe that during this event, the Earth's magnetic field still might protect from the solar wind.